Fuel pump



Aug. 20, 1957 J. H. LocK FUEL PUMP Filed Feb. 19, 1955 .Wb bl, .vu

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United States Patent l FUEL PUMP John Henry Lock, Lapeer, Mich.

Application February 19, 1953, Serial No. 337,790

14 Claims. (Cl. 10S-152) This invention relates to fuel pumps and more particularly to fuel pumps for internal combustion engines.

It is an object of this invention to provide a fuel pump which is quiet in operation and which operates only in response to the demand for fuel by the engine.

In the drawings:

Fig. 1 is a sectional view of a fuel pump embodying the present invention.

Fig. 2 is a sectional View along the line 2 2 in Fig. 1.

Referring to the drawing the fuel pump includes a casing generally designated fashioned with a circular enlargement 12 at one end having a peripheral flange 14 to which a cover member 16 having a peripheral flange 18 may be secured as by screws 20. Between the anges 14 and 18 there is clamped a flexible diaphragm 22. Diaphragm 22 divides the interior of members 12 and 16 into a fuel chamber 24 and an air chamber 26. The casing 1% is provided with a tubular extension 28 in which a stem 30 is axially movable. Stem 30 is connected at one end as at 32 with diaphragm 22 and extends through air chamber 26 into the bore 34 of extension 28. At its free end tubular extension 28 has threaded thereon a hollow cap 36 which closes the outer end of bore 34. A spring 38 acting between extension 28 and diaphragm 22 urges diaphragm 22 and stem 30 in a direction towards the left as viewed in Fig. 1, that is, in a direction tending to decrease the volume of fuel chamber 24.

Chamber 24 is provided with a fuel inlet port 40 and a fuel outlet port 42. Ports 40 and 42 are controlled by check valves 41 and 43 so that fuel is sucked into chamber 24 through port 40 when diaphragm 22 moves towards the right, and fuel is pumped out of cham-ber 24 through port 42 when diaphragm 22 moves towards the left. Port 40 is connected as by a conduit 44 with the fuel tank of the engine, and port 42 is connected as by a conduit 46 with the oat chamber of the carburetor of the engine.

Stem 30 is provided at the free end thereof with a portion 48 of reduced diameter. A valve spool 50 is slidably mounted on the reduced portion 48 of stem 30. Valve S0 is biased in a direction towards the right on the stem portion 48 by a coil spring 52 acting between the end face 54 of the valve and the shoulder portion 56 on stem 30. Valve 50 is biased in the opposite direction on the reduced stem portion 48 by means of a coil spring 58 acting between the opposite end face 60 of valve 50 and a nut 62 which is threaded on the end of the reduced stem portion 48. Valve 50 is`slidable in tubular extension 28 between spaced apart shoulders 64 and 66. Valve 50 is provided with twoannular grooves 68 and 70. The groove 68 is positioned on valve 50 such that when valve 50 abuts against shoulder 64 groove 68 establishes communication between a vacuum port 72 and a passageway 74 in tubular extension 28 which opens into air chamber 2 6. Port 72 is arranged to be connected with the vacuum obtaining in the intake manifold by means of a conduit 76. Groove 70 is located on valve 50 such that when the valve abuts against shoulder 2,803,195 Patented Aug. 20, 1957 66 groove 70 establishes communication between a port 78 which is open to atmosphere and a passageway 80 which opens to air chamber 26.

An oiling wick 82 is arranged to rub against the cylindrical surface of valve 50 as the valve moves between shoulders 64 and `66. Wick 82 is biased radially against the outer cylindrical surface of valve 50 by means of a spring 84 the tension of which is arranged to be adjusted by a spring retainer 86 having a threaded engagement with tubular extension 28 as at 88.

In operation, assuming that the parts are in the positions illustrated in Fig. l, it will be observed that valve 50 abuts shoulder 64 and places vacuum port 72 in communication with vacuum passageway 74 through groove 68 thereby exhausting chamber 26 and causing diaphragm 22 to move to the right. Movement of diaphragm 22 in this direction causes the admission of fuel through inlet 40 into chamber 24. As stem 30 moves to the right, it will be noted that springs 38 and 52 are compressed and spring 58 is expanded. Valve 50 will remain in the position abutting shoulder 64 until the force exerted upon the valve by spring 52 and tending to slide the valve to the right exceeds the restraining effect imposed upon the valve by oiling wick 82. When this occurs spring 52 will slide valve 50 axially to the right to a position where valve 50 abuts against shoulder 66. In this position groove 68 will be moved out of registration with vacuum port 72 and passageway 74, and groove 70 will establish communication between atmosphere port 78 and passageway 80. Thus, atmospheric pressure is admitted to chamber 26 and diaphragm 22 is permitted to flex toward the left under the inuence of compression spring 38. When diaphragm 22 exes towards the left fuel is discharged from chamber 24 through outlet 42.

The rate at which the fuel can be discharged from chamber 24, of course, depends upon the rate at which the fueI is being consumed by the engine, line 46 being connected with the float chamber of the carburetor. Thus, diaphragm 22 and stem 30 move slowly in a direction toward the left in response to the rate of discharge of fuel from chamber 24. During the discharge of fuel from chamber 24, valve 50 will remain in a position wherein the chamber 26 is connected with atmosphere until the force exerted on valve 50 by compression spring 58 exceeds the restraining effect of wick 82 on the cylindrical surface of valve 50. When stem 30 has moved to the left a predetermined distance so that the force exerted on valve 50 by spring 58 exceeds the frictional effect of wick 82, valve 50 slides axially to the left to a position abutting shoulder 64.

Thus, it will be seen that I have provided a compact, very eicient and very quiet fuel pump. The pump operates relatively slowly, diaphragm 22 and stem 30 moving to the left at a rate proportional to the rate at which fuel is consumed by the engine. The fuel pump of this invention therefore avoids many of the objectionable features of fuel pumps with which I am familiar. Valve 50 moves to its two extreme positions relatively slowly; and since stern 30 is not positively driven by mechanical means, the fue! pump does not produce a continuous thumping sound, as is true of conventional fuel pumps with which I am familiar. Furthermore, it will be appreciated that the threaded adjustment of nut 62 and of retainer 86 enables adjustment of the operation of the pump in accordance with the conditions under which the pump is to operate.

The pump may be arranged to be mounted on an engine in any suitable manner. For the purpose of illustrationv the tubular extension 28 is shown fashioned with a lateral projecting portion 90 which forms a mounting bracket for the pump.

I claim:

1. A fuel pump for an internal combustion engine comprising a casing, a diaphragm in said casing dividing the casing into a fuel chamber and an air chamber, a fuel intake and a fuel outlet in said fuel chamber, a stem connected with said diaphragm to move therewith, means biasing said diaphragm in a direction tending to decrease the size of said fuel chamber and to increase the size of said air chamber, a support in which said stem is axially slidable in response to movement of said diaphragm, a pair of passageways communicating with's'aid air chamber, a valve movable in opposite directions to connect said air chamber through one of said passageways with a source of vacuum in one position and through the other f passageway to atmosphere in a second position whereby fuel is pumped into and out of said fuel chamber in response to movement of said valve alternately to said two positions and means for moving said valve to said two positions comprising a pair of springs each operatively connected at one end with said stem and at the opposite end with said valve, one of said springs biasing said valve to move towards said tirst position andthe other spring biasing said valve to move toward said second position and means yieldably resisting movement of said valve against the force applied thereto by said springs.

2. A fuel pump for an internal combustion engine comprising a casing, a diaphragm in said casing dividing the casing into a fuel chamber and an air chamber, a fuel -intake and a fuel outlet in said chamber, said air chamber having a port for connecting said chamber with a source of vacuum and a second port for connecting said air chamber to atmosphere, a stem connected with said dia phragm for movement therewith, a shiftable valve controlling said ports, and a connection between said stem and said valve for shifting said valve to a position opening one of said ports when the stem moves axially in one direction and to a position closing said one port and opening the other of said ports when the valve moves axially in the opposite direction, said connection between said stem and valve including a pair of springs acting between said valve and said stem, one of said springs urging said valve in one direction to a position opening said vacuum port and the other spring urging said valve in the opposite direction towards a position opening said atmosphere port.

3. The combination set forth in claim 2 including means for adjusting the tension of said springs.

4. The combination set forth in claim 2 including friction means acting on said valve and yieldably resisting movement of said valve, said springs when tensioned being of suiiicient strength to overcome the effect of said friction means.

5. A fuel pump for an internal combustion engine comprising a casing, a diaphragm in said casing dividing the casing into a fuel chamber and an air chamber, said fuel chamber having a fuel inlet and a fuel outlet, spring means urging said diaphragm in a direction tending to pump fuel out of said fuel chamber through said fuel outlet, a stem connected with said diaphragm to move therewith, means defining a vacuum passageway communicating with said air chamber, means defining an atmosphere passageway communicating with said air chamber, valve means movable axially in one direction on said stem to a first position connecting said vacuum passageway with a source of vacuum and movable in the opposite direction on said stem to a second position connecting said atmosphere passageway to atmosphere, a pair of opposed springs on said stem each operatively connected at one end with said valve means and at the opposite end with said stem, one of said springs urging said valve means to move in a direction toward said irst position and resisting movement of said valve means in a direction towards said second position, said other spring urging said valve means to move in a direction towardy 4 said second lposition and resisting movement of said valve means in a direction towards said first position, said stem when moved axially in one direction acting through one of said springs to move said valve means to said first position and when moved axially in the opposite direction acting through said other spring to move said valve means to said other position, and means yieldably resisting movement of said valve means until the force acting on the valve means through said springs exceeds a predetermined value.

6. The combination set forth in claim 5 including means for adjusting the tension of said springs to vary the extent through which said stem must move to'produce movement of said valve means.

7. The combination set forth in claim 5 wherein said last mentioned means comprises a friction member having rubbing contact with said valve means, said friction member being arranged to apply a greater restraining effect on said valve means when the valve means is at rest than when the valve means is in motion.

8. The combination set forth in claim 5 wherein said valve means is slidably mounted on said stem and said springs comprise a pair of compression springs on said stem acting against opposite ends of said valve means.

9. The combination set forth in claim 5 including a guide member in which said valve means is slidably mounted and wherein said last mentioned means comprises a rubbing element in said guide member slidably contacting said valve means and yieldably resisting movement thereof.

10. The combination set forth in claim 9 wherein said rubbing member comprises an oiling wick.

ll. The combination set forth in claim 9 including means for varying the pressure with which said rubbing element contacts said valve means.

12. A fuel pump for an internal combustion engine comprising a casing, a exible diaphragm in said casing and dividing said casing into a fuel chamber and an air chamber, said fuel chamber having a fuel inlet and a fuel outlet, said casing also including a tubular extension, a stem mounted for reciprocation in said tubular extension and connected at one end with said diaphragm, an axially reciprocable valve mounted in said tubular extension and having a slidingV connection with said stem, a pair of springs each operatively connected at one end with said valve and at the opposite ends with said stem and biasing said valve in opposite directions in said tubular extension, means limiting the movement of said valve in said tubular extension in opposite directions, means forming vacuum and atmosphere passageways communicating with said air chamber, said valve in one of said extreme positions placing said air chamber in communication with a source of vacuum through said vacuum passageway and when in its other extreme position placing said air chamber in communication with atmosphere through said atmosphere passageway, and means in said tubular extension frictionally engaging said valve and yieldably resisting the movement of said valve against the force exerted on said valve by said springs.

13. The combination set forth in claim 12 wherein said springs engage opposite ends of said valve and including a threaded member on said stern for varying the tension of said springs.

14. The combination set forth in claim 13 wherein said last mentioned means comprises a spring biased member having rubbing contact with the outer surface of said valve and including means for varying the pressure with which said spring biased member bears against said valve.

References Cited in the file of this patent UNITED STATES PATENTS `1,219,938 Hamilton Mar. 20, 1917 1,408,208 Jones Feb. 28, 1922 '2,092,482 v Timian Sept. 7, 1937 

